Coin acceptors that authenticate coins are known. Such devices are typically used in vending machines to identify a currency value assigned to a coin and to validate the coin by confirming that the coin has a set of mechanical characteristics that are consistent with other coins from the same provider (e.g., the U.S. Mint).
The number of different coins accepted by coin acceptors is usually limited. Often quarters are the only coins accepted. Other more sophisticated machines may accept dimes, nickels and even pennies.
At least some coin acceptors may use a set of rails where coins are separated by height. In this case, the rail may have a top support only slightly higher than a dime thereby causing any dimes to fall through the rail into a dime validator. Pennies, nickels and quarters may be subsequently separated using the same concept.
Once separated, each coin may be validated by dropping the respective coins from a predetermined height and validating the respective coins based upon the impact produced. In this case, the impact is measured by the distance that a measuring place is moved by the dropped coin.
While coin validators work well, they are usually limited to the sale of a product. Accordingly, a need exists for more general methods of coin identification.